Add AccentColor Backend (#128)

Move the AccentColorManager from gala to settings-daemon, with the following changes:

* fallback to the primary-color if it fail to get a color from the background.
* properly listen to changes in the PrefersColorScheme property and don't check
  for the accent when not required.

.github/workflows/main.yml

@@ -25,7 +25,7 @@ jobs:
     - name: Install Dependencies
       run: |
         apt update
-        apt install -y libaccountsservice-dev libdbus-1-dev libgranite-dev libgeoclue-2-dev libfwupd-dev libpackagekit-glib2-dev meson valac
+        apt install -y libaccountsservice-dev libdbus-1-dev libgranite-dev libgeoclue-2-dev libfwupd-dev libpackagekit-glib2-dev libgdk-pixbuf2.0-dev libgexiv2-dev meson valac
     - name: Build
       env:
         DESTDIR: out

README.md

@@ -8,7 +8,9 @@ You'll need the following dependencies:
 * libaccountsservice-dev
 * libdbus-1-dev
 * libfwupd-dev
+* libgdk-pixbuf2.0-dev
 * libgeoclue-2-dev
+* libgexiv2-dev
 * libgranite-dev
 * libpackagekit-glib2-dev
 * meson

meson.build

@@ -9,6 +9,8 @@ fwupd_dep = dependency('fwupd')
 gio_dep = dependency ('gio-2.0')
 glib_dep = dependency('glib-2.0')
 granite_dep = dependency('granite', version: '>= 5.3.0')
+gdk_pixbuf_dep = dependency('gdk-pixbuf-2.0')
+gexiv2_dep = dependency('gexiv2')
 pk_dep = dependency('packagekit-glib2')
 i18n = import('i18n')
 gettext_name = meson.project_name()

src/AccountsService.vala

@@ -80,6 +80,7 @@ public interface SettingsDaemon.AccountsService : Object {
 [DBus (name = "io.elementary.pantheon.AccountsService")]
 public interface Pantheon.AccountsService : Object {
     public abstract int prefers_color_scheme { get; set; }
+    public abstract int prefers_accent_color { get; set; }
 }
 
 [DBus (name = "org.freedesktop.DisplayManager.AccountsService")]

src/Application.vala

@@ -17,6 +17,7 @@ public sealed class SettingsDaemon.Application : Gtk.Application {
     private Backends.InterfaceSettings interface_settings;
     private Backends.NightLightSettings night_light_settings;
     private Backends.PrefersColorSchemeSettings prefers_color_scheme_settings;
+    private Backends.AccentColorManager accent_color_manager;
 
     private Backends.Housekeeping housekeeping;
 
@@ -117,6 +118,7 @@ public sealed class SettingsDaemon.Application : Gtk.Application {
         try {
             pantheon_service = yield connection.get_proxy (FDO_ACCOUNTS_NAME, path, GET_INVALIDATED_PROPERTIES);
             prefers_color_scheme_settings = new Backends.PrefersColorSchemeSettings (pantheon_service);
+            accent_color_manager = new Backends.AccentColorManager (pantheon_service);
         } catch {
             warning ("Unable to get pantheon's AccountsService proxy, color scheme preference may be incorrect");
         }

src/Backends/AccentColorManager.vala

@@ -0,0 +1,204 @@
+/*
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ * SPDX-FileCopyrightText: 2021-2024 elementary, Inc. (https://elementary.io)
+ * Authored by: Marius Meisenzahl <mariusmeisenzahl@gmail.com>
+ */
+
+public class SettingsDaemon.Backends.AccentColorManager : Object {
+    public unowned Pantheon.AccountsService accounts_service { get; construct; }
+
+    private Settings background_settings;
+    private Settings interface_settings;
+
+    private enum BackgroundStyle {
+        NONE;
+    }
+
+    private struct Theme {
+        string name;
+        string stylesheet;
+        Gdk.RGBA color;
+    }
+
+    private static inline Gdk.RGBA rgba_from_int (int color) {
+        return {
+            ((color >> 16) & 255) / 255.0,
+            ((color >> 8) & 255) / 255.0,
+            (color & 255) / 255.0,
+            0.0
+        };
+    }
+
+    private static Theme[] themes = {
+        { "Blue",   "io.elementary.stylesheet.blueberry",  rgba_from_int (0x3689e6) }, // vala-lint=double-spaces
+        { "Mint",   "io.elementary.stylesheet.mint",       rgba_from_int (0x28bca3) }, // vala-lint=double-spaces
+        { "Green",  "io.elementary.stylesheet.lime",       rgba_from_int (0x68b723) }, // vala-lint=double-spaces
+        { "Yellow", "io.elementary.stylesheet.banana",     rgba_from_int (0xf9c440) }, // vala-lint=double-spaces
+        { "Orange", "io.elementary.stylesheet.orange",     rgba_from_int (0xffa154) }, // vala-lint=double-spaces
+        { "Red",    "io.elementary.stylesheet.strawberry", rgba_from_int (0xed5353) }, // vala-lint=double-spaces
+        { "Pink",   "io.elementary.stylesheet.bubblegum",  rgba_from_int (0xde3e80) }, // vala-lint=double-spaces
+        { "Purple", "io.elementary.stylesheet.grape",      rgba_from_int (0xa56de2) }, // vala-lint=double-spaces
+        { "Brown",  "io.elementary.stylesheet.cocoa",      rgba_from_int (0x8a715e) }, // vala-lint=double-spaces
+        { "Gray",   "io.elementary.stylesheet.slate",      rgba_from_int (0x667885) }  // vala-lint=double-spaces
+    };
+
+    public AccentColorManager (Pantheon.AccountsService accounts_service) {
+        Object (accounts_service: accounts_service);
+    }
+
+    construct {
+        background_settings = new Settings ("org.gnome.desktop.background");
+        interface_settings = new Settings ("org.gnome.desktop.interface");
+
+        ((DBusProxy) accounts_service).g_properties_changed.connect ((props) => {
+            int accent_color;
+
+            if (!props.lookup ("PrefersAccentColor", "i", out accent_color)) {
+                return;
+            };
+
+            if (accent_color == 0) {
+                background_settings.changed["picture-options"].connect (update_accent_color);
+                background_settings.changed["picture-uri"].connect (update_accent_color);
+                background_settings.changed["primary-color"].connect (update_accent_color);
+                update_accent_color ();
+            } else {
+                background_settings.changed["picture-options"].disconnect (update_accent_color);
+                background_settings.changed["picture-uri"].disconnect (update_accent_color);
+                background_settings.changed["primary-color"].disconnect (update_accent_color);
+            }
+        });
+
+        if (accounts_service.prefers_accent_color == 0) {
+            background_settings.changed["picture-options"].connect (update_accent_color);
+            background_settings.changed["picture-uri"].connect (update_accent_color);
+            background_settings.changed["primary-color"].connect (update_accent_color);
+            update_accent_color ();
+        }
+    }
+
+    private void update_accent_color () {
+        var current_stylesheet = interface_settings.get_string ("gtk-theme");
+        debug ("Current stylesheet: %s", current_stylesheet);
+        Theme? new_theme = null;
+
+        if (background_settings.get_enum ("picture-options") != BackgroundStyle.NONE) {
+            var picture_uri = background_settings.get_string ("picture-uri");
+            debug ("Current wallpaper: %s", picture_uri);
+            new_theme = get_theme_for_picture (picture_uri);
+        }
+
+        // we failed to get a theme from the wallpaper, or the user is using a primary color as background
+        if (new_theme == null) {
+            var primary_color = background_settings.get_string ("primary-color");
+            debug ("Current primary color: %s", primary_color);
+            new_theme = get_theme_for_primary_color (primary_color);
+        }
+
+        if (new_theme.stylesheet != current_stylesheet) {
+            debug ("New stylesheet: %s", new_theme.stylesheet);
+            interface_settings.set_string ("gtk-theme", new_theme.stylesheet);
+        }
+    }
+
+    private Theme? get_theme_for_primary_color (string primary_color) {
+        var best_match = double.MIN;
+        var index = 0;
+
+        Gdk.RGBA color = {};
+        color.parse (primary_color);
+
+        for (var i = 0; i < themes.length; i++) {
+            var match = get_match (color, themes[i].color);
+            if (match > best_match) {
+                best_match = match;
+                index = i;
+            }
+        }
+
+        return themes[index];
+    }
+
+    private Theme? get_theme_for_picture (string picture_uri) {
+        string path;
+        try {
+            path = Filename.from_uri (picture_uri);
+        } catch (ConvertError e) {
+            warning ("Failed to convert picture uri to path: '%s'", e.message);
+            return null;
+        }
+
+        // try to read a theme name from exif metadata
+        try {
+            var metadata = new GExiv2.Metadata ();
+            metadata.open_path (path);
+            var accent_name = metadata.try_get_tag_string ("Xmp.xmp.io.elementary.AccentColor");
+
+            foreach (unowned var theme in themes) {
+                if (theme.name == accent_name) {
+                    return theme;
+                }
+            }
+        } catch (Error e) {
+            warning ("Error parsing exif metadata of \"%s\": %s", path, e.message);
+        }
+
+        // if failed, get a dominant color from the picture
+        try {
+            const double PERCENTAGE_SAMPLE_PIXELS = 0.01;
+
+            var pixbuf = new Gdk.Pixbuf.from_file (path);
+
+            var raw_pixels = pixbuf.get_pixels_with_length ();
+            var factor = pixbuf.has_alpha ? 4 : 3;
+            var step_size = (int) (raw_pixels.length / factor * PERCENTAGE_SAMPLE_PIXELS);
+            var pixels = new Array<Gdk.RGBA> ();
+
+            for (var i = 0; i < raw_pixels.length / factor; i += step_size) {
+                var offset = i * factor;
+                pixels.append_val ({
+                    raw_pixels[offset] / 255.0,
+                    raw_pixels[offset + 1] / 255.0,
+                    raw_pixels[offset + 2] / 255.0,
+                    0.0
+                });
+            }
+
+            var best_match = double.MIN;
+            var index = 0;
+
+            for (var i = 0; i < themes.length; i++) {
+                var match = 0.0;
+
+                foreach (unowned var pixel in pixels) {
+                    match += get_match (pixel, themes[i].color);
+                }
+
+                if (match > best_match) {
+                    best_match = match;
+                    index = i;
+                }
+            }
+
+            return themes[index];
+        } catch (Error e) {
+            warning (e.message);
+        }
+
+        return null;
+    }
+
+    private static inline double get_match (Gdk.RGBA color, Gdk.RGBA other) {
+        var distance = Math.sqrt (
+            Math.pow ((color.red - other.red), 2) +
+            Math.pow ((color.green - other.green), 2) +
+            Math.pow ((color.blue - other.blue), 2)
+        );
+
+        if (distance > 0.25) {
+            return 0.0;
+        }
+
+        return 1.0 - distance;
+    }
+}

src/meson.build

@@ -1,6 +1,7 @@
 sources = files(
     'AccountsService.vala',
     'Application.vala',
+    'Backends/AccentColorManager.vala',
     'Backends/Housekeeping.vala',
     'Backends/InterfaceSettings.vala',
     'Backends/KeyboardSettings.vala',
@@ -20,6 +21,8 @@ executable(
         gio_dep,
         glib_dep,
         granite_dep,
+        gdk_pixbuf_dep,
+        gexiv2_dep,
         libgeoclue_dep,
         m_dep,
         pk_dep